Inorganic substance composition and process for producing same

ABSTRACT

An inorganic substance composition comprising at least 50% by weight of a finely divided inorganic substance and 2 to 50% by weight of a fiber forming organic polymeric material and having a specific surface area of more than 2 m 2  /g is described. The composition is prepared by preparing a liquid suspension from the inorganic substance, the organic polymeric material and a solvent; heating the liquid suspension to at least 100° C to dissolve the organic polymeric material in the solvent; and then extruding the heated liquid suspension at a pressure equal to or higher than the vapor pressure of the solvent through an orifice into a zone of a lower pressure to evaporate the solvent.

This is a continuation of application Ser. No. 428,193 filed Dec. 26,1973 now abandoned.

The present invention relates to a novel inorganic substance compositioncomposed of a predominant amount of a finely divided inorganic substanceand a minor amount of a fiber forming synthetic polymeric materialwherein said finely divided inorganic substance is incorporated so thatits useful properties may effectively be utilized. It also relates to aprocess for producing such an inorganic substance composition.

Attempts have been made to improve or modify the properties of organicpolymeric materials by incorporating finely divided inorganicsubstances, and some of them are widely practiced in the manufacture ofrubber, fibers, papers, molded articles, films and paints. In thesefields finely divided inorganic substances are utilized as a reinforcingagent, or for the purpose of enhancing dimensional stability, rigidity,heat resistance, weatherability or printing properties, or as a fillerto reduce the cost of the product. Inorganic substances have inherentproperties, which cannot be seen in organic polymeric materials, such ashigh resistance to thermal distortion, high rigidity and high surfaceactivity. These useful properties of inorganic substances haveheretofore not been fully utilized in many cases.

It has been found that in order to fully utilize the beneficialproperties of a finely divided inorganic substance it should be presentin the product in an amount of at least 50% by weight based on theweight of the product, and the product should have a specific surfacearea of more than 2m² /g.

Thus, in accordance with one aspect of the present invention there isprovided an inorganic substance composition comprising at least 50% byweight of a finely divided inorganic substance and 2 to 50% by weight ofa fiber forming organic polymeric material and having a specific surfacearea of more than 2 m² /g.

In accordance with another aspect of the present invention there isprovided a process for producing an inorganic substance compositionwhich comprises the steps of:

1. PREPARING A LIQUID SUSPENSION FROM THE FOLLOWING THREE COMPONENTS;

A. a finely divided inorganic substance, in an amount which equals inweight at least 50% of the total weight of this component and component(b) below,

b. a fiber forming organic polymeric material, in an amount which equalsin weight 2 to 100% of the weight of the component (a), and

c. a solvent capable of dissolving the component (b) at a temperature ofat least 100° C.;

2. heating the liquid suspension a temperature of at least 100° C. todissolve the component (b) in the component (c); and then,

3. extruding said heated liquid suspension under a pressure equal to orhigher than the vapor pressure of the component (c) through an orificeinto a zone of a lower pressure to evaporate the component (c)therefrom.

The inorganic substance composition of the present invention ischaracterized as having a specific surface area of at least 2 m² /g,preferably at least 10 m² /g, and being usually in the form of afibril-like, fine fibrous, fine flake-like, arborescent or fineweb-like, porous structure having numerous fine, irregular voidstherein.

The "specific surface area" used herein is the ratio of the surface areaper unit weight of the inorganic substance composition, determined byBET adsorption method. The specific surface area should be at least 2 m²/g and preferably at least 10 m² /g. When the specific surface area islower than 2 m² /g, the inorganic substance composition is restricted inits use. For example, when the inorganic substance composition is usedas an artificial soil, it is poor in hygroscopic property, adsorption ofthe effective components of fertilizer, and promotion in growth ofroots. When used as adsorbent, it is poor in adsorption capacity. Whenused as a filter material, it is poor in filtration capacity. When usedas sheet or paper stock, it is poor in dispersibility in a liquidmedium, beatability and a paper making performance.

The "finely divided inorganic substance" referred to herein meansinorganic particles capable of passing through a 100 mesh screen ofJapanese Industrial Standard and has a maximum size of up to 500 μ.Illustrations of such inorganic substance include, for example, asbesto,alumina, antimony trioxide, barite, calcium carbonate, calcium sulfate,kaolin clay, carbon black, diatomaceous earth, feldspar powder, terraabla, quartz, graphite, magnesium carbonate, magnesium hydroxide,magnesium oxide, mica, molybdenum disulfide, agalmatolite clay,sericite, pyrogenic silica, finely divided silicic acid, silicaamorphous, silica sand, silicate, titanium oxide, whiting, slate powderand the like. These inorganic substances may be used either alone or asa mixture of two or more of these inorganic substances.

The "polymeric material" referred to herein means a fiber-formingorganic linear high molecular weight compound, which may havestabilizers, antistatics, flame retardants and other conventionaladditives. Examples of the polymeric materials are polyolefins, such aspolyethylene, polypropylene, polybutene-1, polystyrene andpolyisobutylene; polyamides such as polyhexamethylene sebacamide,polycaprolactam and polypyrrolydone; polyesters, such as polyethyleneterephthalate, poly-β-valerolactone, and poly-p(β-hydroxyethoxy)benzoate; polycarbonates, polyurethanes, polyethers such aspolyoxymethylene and poly-p-(2,6-dimethylphenoxide); homopolymers andcopolymers of vinyl compounds, such as acrylonitrile, vinyl chloride,vinyl acetate, vinylidene chloride, and methyl methacrylate; a copolymerof vinyl alcohol and ethylene obtained by hydrolysis of a copolymer ofvinyl acetate and ethylene. These polymeric materials may be used eitheralone or as a mixture of two or more of these polymeric materials.

Properties of typical polymeric materials and finely divided inorganicsubstances which may be employed in the practice of the invention arelisted in Tables I and II.

                  Table I                                                         ______________________________________                                                                              Specific                                               Particle               Surface                                 Finely Divided Inorganic                                                                     Size     V.sub.f V.sub.a                                                                             Area                                    Substance      (Micron) (cc/g)  (cc/g)                                                                              (m.sup.2 /g)                            ______________________________________                                        Finely Divided Silicic                                                                       Average                                                        Acid A (SiO.sub.2.nH.sub.2 O)                                                                0.020    0.50    1.91  150                                     Finely Divided Silicic                                                                       Average                                                        Acid B (SiO.sub.2.nH.sub.2 O)                                                                0.040    0.51    2.09  80                                      Diatomaceous Earth                                                                           95%                                                                           10 or    0.55    1.50  20                                                     less                                                           Magnesium Carbonate                                                                          Average                                                                       0.1      0.46    1.81  20                                      Clay           98%                                                                           2 or less                                                                              0.38    0.72  20                                      Talc           98%                                                                           4 or less                                                                              0.37    0.87  13                                      Calcium Carbonate A                                                                          Average                                                                       1.4      0.38    1.10  6                                       Calcium Carbonate B                                                                          Average                                                                       4.0      0.40    0.70  2                                       Magnesium Carbonate/                                                          Calcium Carbonate                                                                            --       0.43    1.39  14                                      (4/3 by weight)                                                               Finely Divided Silicic                                                        Acid B/Calcium Carbonate                                                                     --       0.46    1.49  50                                      (3/2 by weight)                                                               Diatomaceous Earth/                                                           Calcium Carbonate                                                                            --       0.40    1.31  14                                      (4/3 by weight)                                                               Magnesium Carbonate/                                                                         --       0.42    1.29  12                                      Talc (4/3 by weight)                                                          ______________________________________                                    

                  Table II                                                        ______________________________________                                          Polymer        V.sub.p (cc/g)                                                                         Softening point (° C.)                       ______________________________________                                        High Density Polyethylene                                                                      1.05     135                                                 Law Density Polyethylene                                                                       1.10     100                                                 Crystalline polypropylene                                                                      1.09     160                                                 Polyacrylonitrile                                                                              0.86     232                                                 Polyethylene Terephthalate                                                                     0.77     200                                                 Polyvinyl Chloride                                                                             0.70     150                                                 Polystyrene      0.95     160                                                 Nylon-66         0.88     240                                                 Polymethyl Methacrylate                                                                        0.84     140                                                 ______________________________________                                    

In Table I, V_(a) is the bulkiness of the finely divided inorganicsubstance and is measured under a load of 10 kg/cm² in a manner as notedbelow.

The measurement is carried out at a temperature of 25° C. and under dryconditions using a cylinder of 15 cm in height and 2/∵π cm innerdiameter having a removable flat bottom and equipped with a plungermovable up and down by means of an air-cylinder and capable of applyinga load of 10 kg/cm². A predetermined portion (Wg) of the finely dividedinorganic substance to be measured is weighed and placed in thecylinder. The sample in the cylinder is then leveled by gently knockingthe cylinder with a wood hammer. A load of 10 kg/cm² is then applied onthe plunger via the air-cylinder and allowed to stand for 1 minute. Theplunger is then lifted. Another portion (Wg) of the sample is introducedto the cylinder and the general procedure as described above isrepeated. The procedure is repeated 10 times in total. The volume of thesample (10 × Wg) stacked in the cylinder is measured, and the bulkinessof the sample is calculated therefrom. The value of W employed in thismeasurement depends on the particular finely divided inorganic substanceand the process for preparing the substance and is determined in amanner as follows. An appropriate portion of the sample is weighed andplaced in a scaled glass cylinder of an inner diameter of 2/→π cm and alength of 30 cm and having a flat bottom so that the cylinder may befilled to a depth of about 20 cm with the sample. The cylinder is thencaused to fall a distance of 2 cm onto a fixed surface at a rate of 60times per minute. The height of the sample in the cylinder is graduallylowered to an equilibrium value. From this value and the weight of thesample the bulk density of the sample is calculated and adapted as W inthe above measurement.

Values of V_(f) given in Table I were determined by a method inaccordance with JIS-K-5101. Values of softening point and V_(p) given inTable II were determined by methods in accordance with ASTM-D-1526 andJIS-K-6760, respectively.

The inorganic substance composition of the present invention is preparedby the steps of:

1. dispersing a stated amount of a finely divided inorganic substance(component a) and a stated amount of a polymeric material (component b)in a solvent (component c) capable of dissolving said polymeric materialat a temperature of at least 100° C. to produce a liquid suspension;

2. heating the liquid suspension to a temperature of at least 100° C. todissolve the polymeric material in said solvent; and then,

3. extruding the heated liquid suspension under a pressure equal to orhigher than the vapor pressure of said substance through an orifice intoa zone of a lower pressure to evaporate said solvent therefrom.

In the preparation of a liquid suspension from the three components a, band c, mentioned above, both the manner and the order in which the threecomponents are blended with each other are not critical. It is possiblethat water contained in the component a and/or component b will causeproblems when the resulting composition is used in certain fields. Insuch a case, the water contained therein should preferably be removed,for example, by drying prior to the preparation of a liquid suspensionof the three components.

Component c, i.e., a solvent capable of dissolving component b, i.e., apolymeric material at a temperature of least 100° C., should have aboiling point lower than the softening point of the polymeric material,employed and should be capable of dissolving the polymer material, underthe extrusion conditions, i.e., at elevated temperature and pressure.The solvent should be substantially inert to the polymeric material, andconstruction materials of which the employed equipments are composed.

Illustrative of suitable solvents, one can mention, for example,hydrocarbons such as butane, hexane, cyclohexane, pentene, benzene andtoluene; halogenated hydrocarbons such as methylene chloride,chloroform, methyl chloride, propyl chloride, trichloroethylene,trichloroethane, tetrachloroethylene, tetrachloroethane, chlorobenzene,fluorotrichloromethane and 1,1,2-tricycloro-1,2,2-trifluoroethane;alcohols such as methanol, ethanol, propanol and butanol; ketones suchas acetone, cyclopentanone, methyl ethyl ketone and hexafluoroacetone;esters such as methyl acetate, ethyl acetate and γ-butyrolactone, etherssuch as ethyl ether, tetrahydrofuran and dioxane; nitriles such asacetonitrile and propionitrile; and trifluoroacetic acid, carbontetrachloride, carbon disulfide, nitromethane, water, and sulfurdioxide; and a combination thereof. Depending on the nature of theparticular polymeric material, a suitable solvent should be selected.

The liquid suspension of the three components is prepared in a closedvessel and heated to a temperature of at least 100° C. in the vessel todissolve the polymeric material in said solvent. The proportion of thesolvent employed to the mixture of the finely divided inorganicsubstance and the polymeric material should desirably be such that theresulting heated suspension having the polymeric material dissolvedtherein will be flowable enough to be pumped. The heated suspension ismaintained under an autogenous pressure of at least 5 kg/cm², preferablyat least 10 kg/cm², and is extruded under this autogenous pressure orhigher pressures through an orifice into a zone of a lower pressure anda lower temperature, preferably into an ambient atmosphere, to suddenlyevaporate the solvent thereby leaving the desired porous structure. Thelast mentioned operation may be referred to as "spurting".

In the practice of the manufacture of such a structure, any suitableapparatus, including a conventional autoclave, may be employed, providedthat they are equipped with an orifice through which the heated mixturemay be extruded or ejected under elevated temperature and pressures.Conveniently, a continuous extruder can be employed, comprising apressing zone, compressing zone, heating zone, metering zone and anextrusion head having an orifice or orifices.

The porous structure so obtained can be beaten in a liquid mediumincapable of dissolving the polymeric material contained in the porousstructure to be formed into a uniform slurry containing so-calledfibrid. A sheet or paper may be prepared from the fibrid containingslurry by a conventional paper making procedure.

Even if the polymeric material used for the preparation of the porousstructure is a hydrophobic polyolefin, the porous structure can besuccessfully beaten and/or disintegrated in an aqueous medium byblending a minor amount, e.g., 10% by weight based on the weight of theporous structure, of hydrophilic cellulose pulp therewith to provide aslurry, in which fibrid-like structure elements are well dispersed, fromwhich sheets can be made.

The inorganic substance structure of the present invention may also bedispersed in a liquid medium incapable of dissolving the inorganicsubstance structure, such as, for example, methylene chloride andtrichloroethylene, from which dispersion sheets can be made.

Sheet-like structures made from the inorganic substance composition ofthe present invention exhibits enhanced postprocessability when comparedwith similar products obtained by prior art processes, since the formerstructure has lower densities and contains more voids therein, and inconsequence can absorb various treating agents applied thereto to agreater extent. Thus, antistatic agents, flame retardants and otheradditives may readily be applied to the sheet-like structure of theinvention.

The sheet-like structure may be calendered at an appropriatetemperature. It has been found that the calendered products have asurprisingly high initial modulus. They also have enhanced tenacity anddimensional stability. By way of an example, a calendered sheet obtainedby a process in accordance with the invention and comprising 10 parts byweight of high density polyethylene and 90 parts by weight of calciumcarbonate undergoes little or no shrinkage when heated to temperaturesslightly below the melting point of the polyethylene. When fired, itgoes on burning with little or no shrinkage. These results aresurprising and quite unexpected from the behaviours of the comparablesheetlike products of polyolefin prepared by prior art processes, whichundergo shrinkage to a great extent when merely approaching a heatingsource. The calendered sheet of the invention is superior to cellulosepaper in the hydrophobic property.

If desired, the inorganic substance composition of the present inventionmay be used as a filler in a paper-making process. This is advantageousbecause, firstly, the inorganic substance composition provides a yieldhigher than conventional fillers and, secondly, the compositionexercises no harmful influence on the characteristics of the resultingpaper even if the inorganic substance composition is used in a greateramount.

If desired, a sheet-like structure may be prepared from a blend of theinorganic substance composition and a fibrous material such as naturalfibers, synthetic fibers, semi-synthetic fibers, glass fibers, metalfibers and carbon fibers. The sheet-like structure generally has animproved tear strength and a good feel.

The inorganic substance composition of the present invention has severalused besides the sheet-like structure illustrated above. For example, itcan be used as a molding material, a heat-insulation material, a packingmaterial, a sound-proofing material and other construction materials.

The invention will be further described in the following Examples, inwhich finely divided inorganic particle and polymer components are thoseindicated in Tables I and II, unless otherwise specified, and all partsare by weight.

EXAMPLE 1

An autoclave was charged with a mixture of 90 parts of calciumcarbonate, 10 parts of high density polyethylene and 850 parts ofmethylene chloride, sealed, heated to a temperature of 180° C. whilestirring the content, and pressurized to an internal pressure of 40kg/cm² by introducing nitrogen. The conditions were maintained for about10 minutes. At the end of the period, the mixture was spurted through anorifice, provided at the bottom of the autoclave and having a diameterof 1.0 mm, into the atmosphere. The product so obtained was discreteflake-like structures comprising fine porous bodies having a pluralityof voids therein, the thickness of the walls forming each void beingless than 5 micron, and had a specific surface area of 135 m² /g.

EXAMPLES 2 - 53

Following general procedure described in Example 1, a series of mixturesof a polymeric material, finely divided inorganic particles and asolvent as indicated in Table III, were separately spurted underspurting conditions indicated in Table III. The appearance of eachproduct is also shown in the same Table. All the products are porousstructures having numerous fine, irregular voids therein, the wallsforming each void being less than 5 micron in thickness.

                                      Table III                                   __________________________________________________________________________    Example                  Spurting      Specific Surface                       No.    Charged Composition                                                                             Conditions                                                                             Product                                                                            Area (m.sup.2 /g)                      __________________________________________________________________________         High Density Polyethylene                                                                   10 parts                                                                            140° C.                                                                         Fine                                         2   Finely Divided Silicic Acid A                                                               90 parts                                                                            60 kg/cm.sup.2                                                                         powder-                                                                            85                                          Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                                       like                                                                 1 mm     structure                                        High Density Polyethylene                                                                   10 parts                                                                            138° C.                                                                         Fine                                         3   Finely Divided Silicic Acid B                                                               90 parts                                                                            80 kg/cm.sup.2                                                                         sliver-                                                                            75                                          Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                                       like                                                                 1.5 mm   structure                                        High Density Polyethylene                                                                   20 parts                                                    4   Finely Divided Silicic Acid B                                                               80 parts                                                                              "        "  60                                          Methylene Chloride                                                                          800                                                                              parts                                                        High Density Polyethylene                                                                   15 parts                                                                            150° C.                                                                         Fine                                         5   Finely Divided Silicic Acid A                                                               85 parts                                                                            55 kg/cm.sup.2                                                                         flake-                                                                             70                                          Methylene Chloride                                                                          850                                                                              parts                                                                            Orifice Diameter                                                                       like                                                                 1 mm     structure                                        High Density Polyethylene                                                                   30 parts                                                                            150° C.                                        6   Finely Divided Silicic Acid B                                                               70 parts                                                                            62 kg/cm.sup.2                                                                           "  55                                          Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                              1.5 mm                                                    High Density Polyethylene                                                                   5  parts                                                                            200° C.                                        7   Calcium Carbonate A                                                                         95 parts                                                                            60 kg/cm.sup.2                                                                           "  75                                          Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      High Density Polyethylene                                                                   20 parts                                                                            200° C.                                                                         Fine                                         8   Calcium Carbonate B                                                                         80 parts                                                                            60 kg/cm.sup.2                                                                         flake-                                                                             85                                          Methylene Chloride                                                                          750                                                                              parts                                                                            Orifice Diameter                                                                       like                                                                 1 mm     structure                                        High Density Polyethylene                                                                   10 parts                                                                            150° C.                                                                         Fine                                         9   Magnesium Carbonate                                                                         90 parts                                                                            80 kg/cm.sup.2                                                                         sliver-                                                                            80                                          Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                                       like                                                                 1.5 mm   structure                                        High Density Polyethylene                                                                   20 parts                                                                            200° C.                                                                         Fine                                        10   Magnesium Carbonate                                                                         80 parts                                                                            60 kg/cm.sup.2                                                                         flake-                                                                             105                                         Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                                       like                                                                 1 mm     structure                                        High Density Polyethylene                                                                   15 parts                                                                            170° C.                                       11   Magnesium Carbonate                                                                         85 parts                                                                            58 kg/cm.sup.2                                                                           "  120                                         Methylene Chloride                                                                          820                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      High Density Polyethylene                                                                   30 parts                                                                            180° C.                                       12   Diatomaceous Earth                                                                          70 parts                                                                            59 kg/cm.sup.2                                                                           "  95                                          Methylene Chloride                                                                          780                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      High Density Polyethylene                                                                   5  parts                                                                            180° C.                                       13   Diatomaceous Earth                                                                          95 parts                                                                            60 kg/cm.sup.2                                                                           "  69                                          Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      High Density Polyethylene                                                                   5  parts                                                                            190° C.                                                                         Fine                                        14   Clay          95 parts                                                                            62 kg/cm.sup.2                                                                         flake-                                                                             90                                          Methylene Chloride                                                                          750                                                                              parts                                                                            Orifice Diameter                                                                       like                                                                 1 mm     structure                                        High Density Polyethylene                                                                   10 parts                                                                            150° C.                                                                         Fine                                        15   Talc          90 parts                                                                            60 kg/cm.sup.2                                                                         sliver-                                                                            80                                          Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                                       like                                                                 1 mm     structure                                        High Density Polyethylene                                                                   20 parts                                                                            150° C.                                                                         Fine                                        16   Talc          80 parts                                                                            62 kg/cm.sup.2                                                                         flake-                                                                             85                                          Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                                       like                                                                 1 mm     structure                                        High Density Polyethylene                                                                   10 parts                                                                            200° C.                                       17   Finely Divided Silicic Acid A                                                               90 parts                                                                            60 kg/cm.sup.2                                                                           "  110                                         Trichlorotrifluoroethane                                                                    700                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      Crystalline Polypropylene                                                                   10 parts                                                                            140° C.                                       18   Finely Divided Silicic Acid B                                                               90 parts                                                                            60 kg/cm.sup.2                                                                           "  130                                         Methylene Chloride                                                                          780                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      Crystalline Polypropylene                                                                   10 parts                                                                            150° C.                                       19   Finely Divided Silicic Acid B                                                               90 parts                                                                            62 kg/cm.sup.2                                                                           "  140                                         Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      Crystalline Polypropylene                                                                   20 parts                                                                            175° C.                                                                         Fine                                        20   Finely Divided Silicic Acid B                                                               80 parts                                                                            65 kg/cm.sup.2                                                                         flake-                                                                             70                                          Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                                       like                                                                 1 mm     structure                                        Crystalline Polypropylene                                                                   30 parts                                                                            160° C.                                       21   Finely Divided Silicic Acid B                                                               70 parts                                                                            62 kg/cm.sup.2                                                                           "  80                                          Methylene Chloride                                                                          780                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      Crystalline Propylene                                                                       5  parts                                                                            140° C.                                       22   Finely Divided Silicic Acid A                                                               95 parts                                                                            60 kg/cm.sup.2                                                                           "  95                                          Methylene Chloride                                                                          810                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      Crystalline Polypropylene                                                                   10 parts                                                                            150° C.                                       23   Finely Divided Silicic Acid A                                                               90 parts                                                                            60 kg/cm.sup.2                                                                           "  95                                          Methylene Chloride                                                                          810                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      Crystalline Polypropylene                                                                   15 parts                                                   24   Magnesium Carbonate                                                                         85 parts                                                                              "        "  110                                         Methylene Chloride                                                                          800                                                                              parts                                                        Crystalline Polypropylene                                                                   15 parts                                                                            140° C.                                       25   Magnesium Carbonate                                                                         85 parts                                                                            65 kg/cm.sup.2                                                                           "  120                                         Benzene       800                                                                              parts                                                                            Orifice Diameter                                                              1.5 mm                                                    Crystalline Polypropylene                                                                   30 parts                                                                            150° C.                                                                         Fine                                        26   Magnesium Carbonate                                                                         70 parts                                                                            60 kg/cm.sup.2                                                                         flake-                                                                             105                                         Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                                       like                                                                 1 mm     structure                                        Crystalline Polypropylene                                                                   5  parts                                                                            140° C.                                       27   Magnesium Carbonate                                                                         95 parts                                                                            30 kg/cm.sup.2                                                                           "  110                                         Methylene Chloride                                                                          820                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      Crystalline Polypropylene                                                                   5  parts                                                                            150° C.                                                                         Fine                                        28   Calcium Carbonate                                                                           95 parts                                                                            60 kg/cm.sup.2                                                                         sliver-                                                                            60                                          Methylene Chloride                                                                          750                                                                              parts                                                                            Orifice Diameter                                                                       like                                                                 1 mm     structure                                        Crystalline Polypropylene                                                                   5  parts                                                                            160° C.                                                                         Fine                                        29   Calcium Carbonate A                                                                         95 parts                                                                            65 kg/cm.sup.2                                                                         flake-                                                                             80                                          Benzene       650                                                                              parts                                                                            Orifice Diameter                                                                       like                                             Butane        150                                                                              parts                                                                            1 mm     structure                                        Crystalline Polypropylene                                                                   20 parts                                                                            150° C.                                       30   Calcium Carbonate A                                                                         80 parts                                                                            60 kg/cm.sup.2                                                                           "  50                                          Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      Crystalline Polypropylene                                                                   20 parts                                                                            145° C.                                            Finely Divided Silicic Acid/                                                                      60 kg/cm.sup.2                                       31   Calcium Carbonate (3/2 by                                                                         Orifice Diameter                                                                         "  65                                          weight)       80 parts                                                                            1 mm                                                      Methylene Chloride                                                                          800                                                                              parts                                                        Crystalline Polypropylene                                                                   15 parts                                                                            160° C.                                                                         Fine                                        32   Diatomaceous Earth/Calcium                                                                        60 kg/cm.sup.2                                                                         flake                                                                              30                                          Carbonate (4/3 by weight)                                                                   85 parts                                                                            Orifice Diameter                                                                       like                                             Methylene Chloride                                                                          800                                                                              parts                                                                            1 mm     structure                                        Crystalline Polypropylene                                                                   25 parts                                                   33   Diatomaceous Earth                                                                          75 parts                                                                              "        "  25                                          Methylene Chloride                                                                          750                                                                              parts                                                        Crystalline Polypropylene                                                                   30 parts                                                                            150° C.                                       34   Diatomaceous Earth                                                                          70 parts                                                                            65 kg/cm.sup.2                                                                           "  10                                          Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      Crystalline Polypropylene                                                                   15 parts                                                                            160° C.                                       35   Talc          85 parts                                                                            60 kg/cm.sup.2                                                                           "  20                                          Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      Crystalline Polypropylene                                                                   15 parts                                                                            170° C.                                       36   Clay          85 parts                                                                            60 kg/cm.sup.2                                                                           "  25                                          Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      Crystalline Polypropylene                                                                   15 parts                                                                            190° C.                                       37   Talc          85 parts                                                                            65 kg/cm.sup.2                                                                           "  30                                          Cyclohexane   800                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      Polyethylene Terephthalate                                                                  20 parts                                                                            200° C.                                                                         Fine                                        38   Calcium Carbonate                                                                           80 parts                                                                            60 kg/cm.sup.2                                                                         flake-                                           Methylene Chloride                                                                          150                                                                              parts                                                                            Orifice Diameter                                                                       like                                                                 0.5 mm   structure                                        Polyhexamethylene Adipamide                                                                 20 parts                                                                            240° C.                                       39   Finely Divided Silicic Acid A                                                               80 parts                                                                            65 kg/cm.sup.2                                                                           "  95                                          Water         500                                                                              parts                                                                            Orifice Diameter                                                              1.5 mm                                                    Polyoxymethylene                                                                            15 parts                                                                            200° C.                                       40   Finely Divided Silicic Acid B                                                               85 parts                                                                            60 kg/cm.sup.2                                                                           "  110                                         Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                              0.5 mm                                                    Crystalline Polypropylene                                                                   30 parts                                                                            150° C.                                       41   Magnesium Carbonate/Calcium                                                                       55 kg/cm.sup.2                                                                           "  105                                         Carbonate (4/3 by weight)                                                                   70 parts                                                                            Orifice Diameter                                          Methylene Chloride                                                                          800                                                                              parts                                                                            1 mm                                                      Crystalline Polypropylene                                                                   30 parts                                                                            160° C.                                       42   Magnesium Carbonate                                                                         65 parts                                                                            60 kg/cm.sup.2                                                                           "  85                                          Titanium Oxide                                                                              5  parts                                                                            Orifice Diameter                                          Methylene Chloride                                                                          800                                                                              parts                                                                            1 mm                                                      Crystalline Polypropylene                                                                   30 parts                                                   43   Magnesium Carbonate/Talc                                                                            "        "  90                                          (4/3 by weight)                                                                             70 parts                                                        Methylene Chloride                                                                          800                                                                              parts                                                        Crystalline Polypropylene                                                                   20 parts                                                                            160° C.                                                                         Fine                                        44   Low Density Polyethylene                                                                    10 parts                                                                            58 kg/cm.sup.2                                                                         flake-                                                                             80                                          Finely Divided Silicic Acid B                                                               70 parts                                                                            Orifice Diameter                                                                       like                                             Methylene Chloride                                                                          800                                                                              parts                                                                            0.8 mm   structure                                        Polyacrylonitrile                                                                           20 parts                                                                            230° C.                                                                         Fine                                        45   Finely Divided Silicic Acid A                                                               80 parts                                                                            80 kg/cm.sup.2                                                                         sliver-                                                                            105                                         Water         300                                                                              parts                                                                            Orifice Diameter                                                                       like                                             Acetonitrile  500                                                                              parts                                                                            1 mm     structure                                        Crystalline Polypropylene                                                                   20 parts                                                                            190° C.                                                                         Fine                                             Polymethyl Methacrylate                                                                     10 parts                                                                            80 kg/cm.sup.2                                                                         flake-                                      46   Magnesium Carbonate                                                                         70 parts                                                                            Orifice Diameter                                                                       like 90                                          Methylene Chloride                                                                          600                                                                              parts                                                                            1 mm     structure                                        Butane        200                                                                              parts                                                        Polyethylene Terephthalate                                                                  10 parts                                                                            200° C.                                            Finely Divided Silicic Acid A/                                                                    63 kg/cm.sup.2                                       47   Calcium Carbonate (3/2 by                                                                         Orifice Diameter                                                                         "  75                                          weight)       90 parts                                                                            0.5 mm                                                    Methylene Chloride                                                                          200                                                                              parts                                                        High Density Polyethylene                                                                   20 parts                                                                            230° C.                                       48   Magnesium Carbonate                                                                         80 parts                                                                            65 kg/cm.sup.2                                                                           "  80                                          Hexane        750                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      Polyvinyl Chloride                                                                          20 parts                                                                            200° C.                                                                         Fine                                        49   Finely Divided Silicic Acid                                                                 80 parts                                                                            80 kg/cm.sup.2                                                                         flake-                                                                             73                                          Methylene Chloride                                                                          300                                                                              parts                                                                            Orifice Diameter                                                                       like                                             Hexane        50 parts                                                                            0.8 mm   structure                                        Low Density Polyethylene                                                                    10 parts                                                                            180° C.                                       50   Finely Divided Silicic Acid B                                                               90 parts                                                                            60 kg/cm.sup.2                                                                           "  140                                         Methylene Chloride                                                                          500                                                                              parts                                                                            Orifice Diameter                                                              0.8 mm                                                    Low Density Polyethylene                                                                    5  parts                                                                            180° C.                                       51   Magnesium Carbonate                                                                         95 parts                                                                            55 kg/cm.sup.2                                                                           "  140                                         Methylene Chloride                                                                          600                                                                              parts                                                                            Orifice Diameter                                                              0.8 mm                                                    Low Density Polyethylene                                                                    10 parts                                                                            160° C.                                       52   Finely Divided Silicic Acid A                                                               90 parts                                                                            60 kg/cm.sup.2                                                                           "  150                                         Methylene Chloride                                                                          750                                                                              parts                                                                            Orifice Diameter                                                              0.8 mm                                                    Low Density Polyethylene                                                                    15 parts                                                   53   Diatomaceous Earth                                                                          85 parts                                                                              "        "  100                                         Methylene Chloride                                                                          700                                                                              parts                                                   __________________________________________________________________________

EXAMPLE 54

An autoclave was charged with a mixture of 10 parts of an ethylene-vinylacetate copolymer containing 12% by weight of vinyl acetate and aspecific volume of 1.08, 90 parts of finely divided silicic acid A and800 parts of methylene chloride, sealed, heated to a temperature of 160°C. while stirring the content, and pressurized to an internal pressureof 60 kg/cm² by introducing nitrogen. The conditions were maintained forabout 15 minutes. At the end of the period, the mixture was spurtedthrough an orifice, provided at the bottom of the autoclave and having adiameter of 1.0 mm, into the atmosphere.

The product so obtained was discrete porous, flake-like structureshaving numerous fine, irregular voids therein and had a specific surfacearea of 90 m² /g.

EXAMPLE 55

A slurry preparing tank was charged with a mixture of 15 parts ofcrystalline polypropylene powder, 85 parts of a finely divided silicicacid A, 0.2 part of β-(4-hydroxy-3,5-di-tert-butylphenyl) propionic acidester of pentaerythrytol (antioxidant) and 800 parts of methylenechloride to prepare a slurry. The slurry was transferred by a liquidtransferring pump, provided at the bottom of the slurry preparing tank,through a pipe to a heating zone where the slurry was heated to atemperature of 150° C. Then, the slurry was transferred into ahomogenizing vessel maintained at a temperature of 150° C. to prepare ahomogeneous slurry. The slurry was spurted at a pressure of 58 kg/cm²through an orifice of an extrusion head, connected with the bottom ofthe homogenizing vessel, into the atmosphere. The orifice had a diameterof 1.0 mm.

The product so obtained was discrete porous, flake-like structureshaving numerous fine, irregular voids therein and had a specific surfacearea of 80 m² /g.

EXAMPLES 56 - 64

Following the general procedure described in Example 55, porousstructures having numerous fine, irregular voids therein were preparedseparately from a series of mixtures of a polymeric material, finelydivided inorganic substance and a solvent as indicated in Table IV. Thecomposition of the mixtures, the spurting conditions, and the appearanceof each product are shown in Table IV.

                                      Table IV                                    __________________________________________________________________________    Example                  Spurting      Specific Surface                       No.     Charged Composition                                                                            Conditions                                                                             Product                                                                            Area (m.sup.2 /g)                      __________________________________________________________________________         High Density Polyethylene                                                                   20 parts                                                                            220° C.                                                                         Fine                                        56   Finely Divided Silicic Acid B                                                               80 parts                                                                            68 kg/cm.sup.2                                                                         sliver-                                                                            105                                         Methylene Chloride                                                                          650                                                                              parts                                                                            Orifice Diameter                                                                       like                                             Butane        50 parts                                                                            1 mm     structure                                        High Density Polyethylene                                                                   15 parts                                                                            155° C.                                                                         Fine                                        57   Finely Divided Silicic Acid B                                                               85 parts                                                                            60 kg/cm.sup.2                                                                         flake-                                                                             100                                         Methylene Chloride                                                                          820                                                                              parts                                                                            Orifice Diameter                                                                       like                                                                 0.5 mm   structure                                        High Density Polyethylene                                                                   15 parts                                                                            150° C.                                       58   Finely Divided Silicic Acid A                                                               85 parts                                                                            58 kg/cm.sup.2                                                                           "  120                                         Methylene Chloride                                                                          850                                                                              parts                                                                            Orifice Diameter                                                              0.5 mm                                                    High Density Polyethylene                                                                   15 parts                                                                            200° C.                                       59   Magnesium Carbonate                                                                         85 parts                                                                            62 kg/cm.sup.2                                                                           "   85                                         Methylene Chloride                                                                          750                                                                              parts                                                                            Orifice Diameter                                                              1 mm                                                      High Density Polyethylene                                                                   20 parts                                                                            160° C.                                       60   Magnesium Carbonate                                                                         80 parts                                                                            60 kg/cm.sup.2                                                                           "   75                                         Methylene Chloride                                                                          800                                                                              parts                                                                            Orifice Diameter                                                              0.5 mm                                                    Crystalline Polypropylene                                                                   15 parts                                                                            150° C.                                                                         Fine                                        61   Finely Divided Silicic Acid A                                                               85 parts                                                                            58 kg/cm.sup.2                                                                         flake-                                                                             105                                         Methylene Chloride                                                                          820                                                                              parts                                                                            Orifice Diameter                                                                       like                                                                 0.5 mm   structure                                        Crystalline Polypropylene                                                                   15 parts                                                                            155° C.                                       62   Magnesium Carbonate                                                                         85 parts                                                                            60 kg/cm.sup.2                                                                           "  85                                          Methylene Chloride                                                                          750                                                                              parts                                                                            Orifice Diameter                                                              0.5 mm                                                    High Density Polyethylene                                                                   20 parts                                                                            160° C.                                       63   Calcium Carbonate A                                                                         80 parts                                                                            58 kg/cm.sup.2                                                                           "  70                                          Benzene       500                                                                              parts                                                                            Orifice Diameter                                                              1.0 mm                                                    Crystalline Polypropylene                                                                   30 parts                                                                            155° C.                                       64   Magnesium Carbonate/                                                                              57 kg/cm.sup.2                                                                           "  60                                          Calcium Carbonate (4/3)                                                                     70 parts                                                                            Orifice Diameter                                          Methylene Chloride                                                                          800                                                                              parts                                                                            0.5 mm                                               __________________________________________________________________________

What we claim is:
 1. An inorganic substance composition comprising about95% by weight of a finely divided inorganic substance and about 5% byweight of a fiber forming organic linear high molecular weight syntheticpolymeric material; said inorganic substance composition being in theform of fine fibrous-like, flake-like or sliver-like structures andhaving a specific surface area of at least 10 m² /g and a porousstructure containing a plurality of fine, irregular voids therein, thewall forming each void being less than 5 micron in thickness.
 2. Aninorganic substance composition according to claim 1, wherein saidfinely divided inorganic substance has a maximum size of up to 500micron.
 3. An inorganic substance composition according to claim 1,wherein said finely divided inorganic substance is at least one selectedfrom the group consisting of finely divided silicic acid, diatomaceousearth, magnesium carbonate, clay, talc, calcium carbonate, titaniumoxide, graphite, carbon black, mica, antimony trioxide, asbesto, aluminaand calcium sulfate.
 4. An inorganic substance composition according toclaim 1, wherein said fiber forming organic polymeric material ispolyethylene.
 5. An inorganic substance composition according to claim1, wherein said fiber forming organic polymer material is polypropylene.6. An inorganic substance composition according to claim 1, wherein saidfiber forming organic polymeric material is polyethylene terephthalate.7. An inorganic substance composition according to claim 1, wherein saidfiber forming organic polymeric material is polyacrylonitrile or acopolymer containing at least 50% by weight of acrylonitrile.
 8. Aninorganic substance composition according to claim 1, wherein said fiberforming organic polymeric material is polyvinyl chloride.
 9. Aninorganic substance composition according to claim 1, wherein said fiberforming organic polymeric material is polymethyl methacrylate or acopolymer containing at least 50% by weight of methyl methacrylate. 10.An inorganic substance composition according to claim 1, wherein saidfiber forming organic polymeric material is at least one selected from acopolymer of vinyl acetate and ethylene, and a product prepared byhydrolysis of said copolymer.